1. This Order may be cited as the Standard Specification (Extenders for Paints) Order, 1949.

(1) The specification set forth in Part II of the Schedule to this Order is hereby declared to be the standard specification for the commodity described in Part I of the said Schedule.

(2) The said standard specification may be cited as Irish Standard 19: 1949.

SCHEDULE.

PART I.

EXTENDERS FOR PAINTS.

PART II.

SPECIFICATION.

In this specification, the letters I.S., when followed by two sets of numbers, refer to the Irish Standard of which the first is the serial number and the second the year of its promulgation by the Minister for Industry and Commerce.

In this specification, the letters B.S., when followed by two sets of numbers, refer to the British Standard of which the first is the serial number, and the second is the year of its publication by the British Standards Institution.

SCOPE

1. This specification applies to the following materials in their use as extenders for paints :—

Asbestine,

Barytes,

Blanc fixe,

Silica,

Whiting,

PHYSICAL CONDITION

2. Extenders shall be either in the form of a dry soft powder, or in a form such that they may be crushed to that form with a palette knife.

The particles of an extender, when examined under a microscope, shall closely resemble those of an agreed sample in shape and size.

COMPOSITION

3. Each extender when dried at a temperature of 98 to 102° C., shall have the composition set out for it below.

Abestine shall consist essentially of a naturally occurring hydrated magnesium silicate which may have been bleached.

Barytes shall consist of natural barium sulphate which may have been bleached and shall contain not less than 90 per cent. of barium sulphate (BaSO4).

Blanc Fixe shall consist of barium sulphate produced by precipitation. It shall contain not less than 96 per cent. barium sulphate and not less than 98 per cent. of insoluble barium compounds.

Silica shall contain not less than 98 per cent. of silicon dioxide (SiO2)

Whiting shall contain not less than 95 per cent of calcium carbonate (CaCO3).

CONTENT OF COARSE PARTICLES

4. The content of coarse particles, when determined in the manner described in Appendix A, shall not be greater than :—

0·5 per cent. for Asbestine,

0·25 " " " Barytes,

0·1 " " " Blanc Fixe,

0·5 " " " Silica,

0·5 " " " Whiting

Blanc Fixe when tested in the manner described in Appendix A shall leave no residue on a No. 100 test sieve conforming to B.S. 410 : 1943.

OIL ABSORPTION

5. The oil absorption number of the extender when determined in the manner described in Appendix B, shall be within plus or minus 10 per cent. of the oil absorption number of the agreed sample of that extender when treated similarly and at the same time.

Alternatively, the oil absorption number for asbestine shall be not less than 25 and not more than 30 and for barytes not less than 8 and not more than 12.

COLOUR

6. The colour of asbestine or of barytes shall closely match that of the agreed sample, if any, when compared in the manner described in Appendix C.

The colour of blanc fixe, silica, or Whiting shall closely match that of the agreed sample, if any, when compared either (a) in the dry state, or (b) in the manner described in Appendix C.

REDUCING POWER OF BLAND FIXE

7. The reducing power of blanc fixe shall be close to, and shall not be inferior to that of the agreed sample, if any, when compared in the manner described in Appendix D.

VOLATILE MATTER

8. The percentage loss in weight of an extender when heated to constant weight in an oven maintained at 100± 2° C. shall not exceed :—

0·75 for Asbestine,

0·5 " Barytes,

0·5 " Blanc Fixe,

1·0 " Silica,

1·0 " Whiting.

MATTER SOLUBLE IN WATER, ACIDITY, ALKALINITY

9. The percentage of matter soluble in water, and the acidity or alkalinity of the aqueous extracts determined by the methods described in Appendix E, shall be not greater than the values set out for the extender in Table 1.

TABLE I.

Extender

Matter soluble in water

Acidity

Alkalinity

Asbestine

0·25

—

—

Barytes

2·0

0·0

0·0

Blanc Fixe

0·5

0·1

0·1

Silica

0·5

0·0

0·0

Whiting

0·5

—

0·1

CARBONATES IN BARYTES AND BLANC FIXE

10. The proportion of carbonates calculated as carbon dioxide (CO2) present in barytes and blanc fixe shall not exceed 1·5 per cent. and 0·1 per cent. respectively.

METHOD OF SAMPLING AND SIZE OF SAMPLE

11. Representative samples, each weighing not less than 1lb., shall be taken in triplicate from one or more original and previously unopened containers, or from the bulk during filling. They shall be packed in clean, dry, air-tight, non-absorbent containers madeof material on which the sample has no action. The containers shall be of a size such that they are nearly filled by the sample. Each container so filled shall be sealed and shall be marked with the date of sampling, and with sufficient information to identify the sample.

AGREED SAMPLE

12. Except where otherwise agreed between the Purchaser and Vendor, the agreed sample referred to in this specification shall comply in all respects with the requirements of this specification. The sample shall weigh not less than 1 lb. and shall be packed in the manner described in Clause 11.

APPENDIX A.

Method for the Determination of the Content of Coarse Particles.

The appropriate quantities of extenders to be used in this determination shall be :—

Asbestine 10 g.

Barytes 25 g.

Blanc Fixe20 g.

Silica 20 g.

Whiting 20 g.

The appropriate quantity of the extender shall be placed on a plate of glazed porcelain or ground glass or marble. Refined linseed oil conforming to I.S. 14: 1949 shall be added and rubbed in thoroughly with a palette knife until a smooth paste is obtained.

The paste shall be mixed with 100 ml. of white spirit and the mixture transferred by washing with the white spirit to a No. 240 test sieve conforming to B.S. 410 : 1943. The residue remaining on the sieve shall be washed with white spirit, not under pressure, and gently brushed with a soft camel-hair pencil until the washings are clear. The final residue shall be dried for one hour in an oven at 100± 2° C. and weighed. The residue calculated as a percentage of the original sample shall be taken as the percentage of coarse particles.

In determining the content of the coarse particles of blanc fixe, the blanc fixe before being washed through the No. 240 test sieve shall be washed through a No. 120 test sieve conforming to B.S. 410 : 1943 and the residue thereon treated as above.

The white spirit used in this determination shall conform to I.S. 11 : 1949.

APPENDIX B.

Method for the Determination of the Oil Absorption.

The appropriate quantities of extenders to be used in this determination shall be :—

Asbestine 20 g.

Barytes 20 g.

Blanc Fixe 10 g.

Silica 10 g.

Whiting 10 g.

The appropriate quantity of the extender shall be placed on a plate of glazed porcelain or ground glass, or marble. Refined linseed oil conforming to I.S. 14 : 1949 shall be added gradually and rubbed thoroughly into the whole of the extender with a palette knife until a coherent mass is obtained. The rate of addition of the linseed oil shall be regular and the incorporation of the oil with the extender shall occupy 20 minutes. The weight of the oil used shall be noted and the oil absorption number of the extender shall be calculated as the weight of oil required by 100 g. of the extender.

The oil absorption number of the agreed sample shall be determined in a similar manner and at the same time.

APPENDIX C.

Method for the Comparison of Colour.

Silica shall be rubbed down to a smooth paste with refined linseed oil using a glass or marble muller. Additional refined linseed oil shall be incorporated in sufficient quantity to give a mixture which can be evenly spread on a smooth surface.

Other extenders shall be rubbed down to paint consistency, with a glass or marble muller, using a mixture of 4 parts by volume of refined linseed oil to 1 part by volume of turpentine or white spirit.

The agreed sample shall be treated in the same way and at the same time as the corresponding extender and the two mixtures so prepared shall be of the same apparent consistency.

The two mixtures shall be spread in the same direction in alternate strips on a clear colourless glass plate. These strips shall be not less than ¾ in. wide and shall have touching edges not less than 1½ in. long. The strips shall be compared in diffused daylight immediately after application.

Ten grams of the blanc fixe shall be made into a smooth stiff paste with refined linseed oil. Vegetable black (0·1 g.), conforming to B.S. 286 : 1937, shall be thoroughly rubbed out with refined linseed oil on a non-absorbent slab for five minutes, using a glass or marble muller.

The black-in-oil and the blanc fixe paste shall then be thoroughly incorporated and rubbed out on a non-absorbent slab until no further change in colour is manifest and the whole has been formed into a smooth paste of consistency such that it is capable of being evenly spread on a smooth surface.

A mixture shall be prepared from the agreed sample, by treating it in the same way and at the same time as above, and reducing it to the same apparent consistency by the addition of refined linseed oil.

The two mixtures shall be spread in the same direction in alternate strips on a clear colourless glass plate. These strips shall be not less than ¾ in. wide and shall have touching edges of not less than 1½ in. in length. The strips shall be compared in diffused daylight immediately after application. Refined linseed oil used in this determination shall conform to I.S. 14 : 1949.

APPENDIX E.

Methods for the Determination of Matter Soluble in Water, and Acidity, or Alkalinity.

Twenty grams of silica or 5 g. of other extender shall be wetted thoroughly with 2 ml. of ethyl alcohol and then boiled for five minutes with 200 ml. of neutral distilled water. The mixture shall then be cooled to room temperature, made up to 250 ml. with neutral distilled water, shaken and filtered. After rejection of the first 50 ml., a measured quantity of the filtrate shall be evaporated to dryness. The residue so obtained shall be dried to constant weight in an oven maintained at a temperature of 100 ± 2° C. This weight expressed as a percentage of the original weight of the extender shall be taken as the percentage of matter soluble in water.

The acidity or alkalinity shall be determined by titrating further aliquot portions of the filtrate using methyl red as indicator. The acidity shall be calculated on the material as the percentage equivalent of sulphuric acid (H2SO4). The alkalinity shall be calculated on the material as the percentage equivalent of sodium carbonate (Na2CO3).